CYFLWYNIAD INTRODUCTION Mae Cyngor a Network Rail yn bwriadu and Network Rail propose to replace adeiladu pont newydd i gario’r ffordd a’r rheilffordd sy’n the Pont Briwet road and rail viaduct that spans the croesi Afon Dwyryd a hefyd wella’r ffyrdd sy’n dod ati. Afon Dwyryd and improve the approach roads on Mae Pont Briwet 1 cilometr i’r de-ddwyrain o either side. Pont Briwet is loctaed 1km south-east of Benrhyndeudraeth yng Ngwynedd, gogledd-orllewin in Gwynedd, north-west Wales. Cymru. Mae’r cynllun arfaethedig rhwng cyferinodau’r The proposed scheme is located between national grid grid cenedlaethol SH612388 a SH621375. references SH612388 and SH621375.

Mae Pont Briwet mewn cyflwr gwael ar hyn o bryd ac Pont Briwet is currently in a poor condition and needs mae’n rhaid ei chynnal a’i chadw’n rheolaidd. Bydd regular maintenance, with some major repairs angen gwaith trwsio mawr arni yn y dyfodol agos. required in the near future. A 2 tonne weight Oherwydd cyfyngiad pwysau o 2 dunnell mae’n rhaid i gerbydau mwy wneud taith gylch o 8 cilometr o amgylch restriction requires larger vehicles to take an 8 mile aber afon Ddwyryd drwy Faentwrog. Does yna ddim detour around the Dwyryd estuary via . darpariaeth benodol i gerddwyr a beicwyr groesi Pont There is no dedicated provision for pedestrians or Briwet. Mae’n debyg y bydd rhagor o draffig yn croesi’r cyclists across Pont Briwet. Future pressure on the bont ac yn defnyddio’r ffyrdd tuag ati ar ôl agor ffordd bridge and approach roads is likely to arise from the osgoi A487 , Minffordd a Thremadog a bydd opening of the A487 Porthmadog, Minffordd and angen dar gyfeirio loriau trymion oddi wrth Tremadog bypass and a need to divert HGV vehicles Benrhyndeudraeth a Maentwrog. away from Penrhyndeudraeth and Maentwrog.

Bwriedir, felly, newid y ddarpariaeth annigonol bresennol, It is therefore proposed to replace the current, ar y ffordd ac ar y rheilffordd, gyda phont fodern, inadequate road and rail provision with a modern, ddiogelach a chynaliadwy a fydd yn cynnws safer and sustainable structure, including dedicated darpariaethau ar gyfer defnyddwyr ffordd a rheilffordd, facilities for road and rail users, cyclists and beicwyr a cherddwyr a gwella’r ffyrdd tuag ati hefyd. pedestrians and improvements to both approach roads. Crynodeb Annhechnegol yw hwn o'r Datganiad Amgylcheddol a gyflwynir yn unol â Chyfarwyddeb y This is the Non Technical Summary (NTS) of the Comisiwn Ewropeaidd 85/337/EEC a newidiwyd gan Environmental Statement (ES) issued in accordance gyfarwyddebau’r Comisiwn Ewropeaidd 97/11/EC a with EC Directive 85/337/EEC as amended by EC 2003/35/EC, a gymhwysir gan Adran 71A Deddf Directives 97/11/EC and 2003/35/EC, as applied by Cynllunio Gwlad a Thref 1990 ac a weithredir gan Reoliadau Cynllunio Gwlad a Thref (Asesiad o Effeithiau Section 71A of the Town and Country Planning Act Amgylcheddol) 1990 (OS 1999 Rhif 293), fel y'i 1990 and implemented by The Town and Country newidiwyd. Planning (Environmental Impact Assessment) (England and Wales) Regulations 1999 (SI 1999; No. 293), as amended.

Lleoliad y Cynllun Arfaethedig / Location of the Proposed Scheme DATGANIAD AMGYLCHEDDOL ENVIRONMENTAL STATEMENT Mae'r Datganiad Amgylcheddol yn nodi, yn disgrifio ac yn The ES identifies, describes and assesses the potential asesu'r effeithiau amgylcheddol a allai godi o’r cynllun environmental impacts of the proposed scheme and arfaethedig ac mae’n amlinellu unrhyw waith lliniaru sydd outlines any mitigation measures required to avoid, ei angen i osgoi, lleihau ac, os yn bosibl, lleihau drwg reduce and, if possible, offset the major adverse effeithiau mwyaf y prosiect. Mae hefyd yn cyflwyno effects of the project. It also provides relevant gwybodaeth berthnasol ynghylch dyluniad y cynllun information regarding the design of the proposed arfaethedig a'r prif gynlluniau amgen er mwyn galluogi'r scheme and the main alternatives to enable the Local Awdurdod Cynllunio Lleol eu hystyried cyn penderfynu a Planning Authority to take into consideration before ddylid rhoi caniatâd cynllunio ai peidio i’r prosiect. deciding whether or not to grant planning permission

for the project. Mae’r Datg aniad Amgylcheddol yn cynnwys y dogfennau canlynol: Cyfrol 1: y Datganiad Amgylcheddol - dogfen The ES includes the following documents: gynhwysfawr yn casglu'r holl wybodaeth berthnasol Volume 1: the ES - a comprehensive and concise ynghylch y cynllun arfaethedig. document drawing together all relevant information Crynodeb Anhechnegol: crynodeb byr, dwyieithog o about the proposed scheme. brif ganfyddiadau Cyfrol 1 y Datganiad Amgylcheddol Non-technical Summary: a bilingual, brief summary mewn iaith annhechnegol. of the main findings of Volume 1 of the ES in a non- Cyfrol 1a: Ffigurau ar gyfer y Datganiad Amgylcheddol technical language. - gan gynnwys y cynlluniau y mae Cyfrol 1 yn cyfeirio Volume 1a: Figures for the Environmental Statement atyn nhw. - containing plans to which Volume 1 (ES) refers. Cyfrol 2: mae hon yn cynnwys adroddiadau technegol Volume 2: Detailed technical reports of some of the manwl ar y pynciau amgylcheddol sy’n cael eu disgrifio environmental topics described in Volume 1. yng Nghyfrol 1. The full ES and associated documents will be Bydd y Dat ganiad Amgylcheddol llawn a’r dogfennau forwarded to the National Park Authority in cysylltiedig yn cael eu hanfon at Awdurdod Parc conjunction with the planning application submission Cenedlaethol Eryri fel rhan o’r cais cynllunio a gyflwynir for the proposed scheme. ar gyfer y cynllun arfaethedig.

In accordance with Regulation 61 of The Conservation Yn unol â Rheoliad 61 o Reoliadau Cadwraeth of Habitats and Species Regulations 2010 a Statement Cynefinoedd a Rhywogaethau 2010, bydd Datganiad i to Inform an Appropriate Assessment (SIAA) of the Hysbysu Asesiad Priodol o’r effeithiau y gallai’r cynllun arfaethedig ei gael ar Ardal Cadwraeth Arbennig Pen Llyn possible impacts associated with the proposed scheme a’r Sarnau hefyd yn cael eu hanfon at yr Awdurdod on the Lleyn Peninsula and the Sarnau SAC will also Cymwys. Mae’n rhaid i'r Awdurdod Cymwys gynnal yr be forwarded to the Competent Authority (SNPA). Asesiad Priodol cyn rhoi caniatâd i weithredu’r cynllun The Appropriate Assessment must be undertaken by arfaethedig. the Competent Authority prior to approval being given to implement the proposed scheme. Y SEFYLLFA BRESENNOL Pan adeiladwyd traphont Pont Briwet yn niwedd y THE EXISTING SITUATION 1860’au, disodlodd y gwasanaeth fferi ar Afon Dwyryd. Pont Briwet viaduct was built in the late 1860’s to Cafodd ei hail adeiladu’n rhannol ym 1921 a’i hailadeiladu replace a ferry service on the Afon Dwyryd. It was bron yn gyfan gwbl ym 1932. Gwnaed y gwaith partially rebuilt in 1921 and largely reconstructed in diweddaraf arni yn 2007 / 2008. Mae wedi’i gosod fras 1932. The most recent work was in 2007/2008. It is o’r de i’r go gledd ac yn cario un trac o reilffordd Cyffordd orientated approximately north – south and carries a Dyfi i Bwllheli (rheilffordd Arfordir y Cambrian) sy’n single track of the Dovey Junction – Pwllheli railway cysylltu â Rheilffordd y Cambrian (Amwythig i (the Cambrian Coast railway line), which links with the Aberystwyth) yng Nghyffordd Dyfi. (Shrewsbury – Aberystwyth) at Dovey Junction. Mae un ffordd doll, un lôn, yn cael ei rheoli gan oleuadau ar ochr ddwyreiniol (i fyny’r afon) y draphont. There is a single lane, traffic light-controlled toll road Gwaherddir cerbydau trymach na 2 dunnell arni, sy’n on the eastern (upstream) side of the viaduct. This golygu na all loriau trymion groesi’r bont. Mae’n rhaid iddn nhw ddargyfeirio 8 milltir (bob ffordd) drwy has a 2 tonne weight restriction, which means that Faentwrog. Mae’r ffordd dros y bont yn un ddi- larger vehicles are unable to use the bridge and ddosbarth ond mae’n gyswllt cyfleus rhwng instead must make an 8 mile (each way) detour via Penrhyndeudraeth i’r gogledd a’r A496 a’i phentrefi a’i Maentwrog. The road over the bridge is unclassified threfi, megis , i’r de. Mae’r cyfyngiadau but provides a convenient link between cyflymder o 20 milltir yr awr ar y draphont, y goleuadau Penrhyndeudraeth to the north and the A496 and traffig sy’n rheoli symudiadau cerbydau ar y bont a’r settlements such as Harlech to the south. The speed tolldy ar y pen gogoleddol yn aml yn achosi tagfeydd. restriction of 20mph across the bridge, signal- controlled, one-way traffic management and toll at the northern end often lead to traffic congestion. Mae’r ffordd yn gul dros y bont ac nid ysytyrir ei bod The road width over the bridge is limited and is not yn addas ar gyfer cerddwyr na marchogion. Mae’r considered suitable for pedestrian or equestrian use. bont a’r ffyrdd tuag ati yn rhan o Lwybr Rhif 8 The bridge and approaches are part of the National Rhwydwaith Beicio Cenedlaethol Ar y Ffordd. Mae’n Cycle Network On-road Route Number 8 and are wybuddus bod beicwyr yn ei defnyddio er ei bod mor known to be used by cyclists, although the currently gul. narrow layout is considered unfavourable.

Ffyrdd preifat yn bennaf sy’n cysylltu â dwy ben y The northern and southern approaches are mainly bont, ac mae’r rhain yn arwain at y rhwydwaith ffyrdd privately-owned roads that connect with the road ym Mhenrhyndeudraeth a Chilfor. Mae’r rhain mewn network at Penrhyndeudraeth and Cilfor. These are in cyflwr rhesymol ond yn gul iawn, un lôn mewn a reasonable condition but are very narrow, effectively gwirionedd ac o safon ddylunio israddol o ran single track and of a low design standard in terms of blaenwelededd, yn enwedig wrth ddod at Bont Briwet forward visibility; particularly on the northern o’r gogledd ac ar y tro ger gorsaf . approach to Pont Briwet and at the bend adjacent to Llandecwyn halt. Mae diddordeb ac ansawdd amgylchedd a thirlun yr ardal yn sylweddol ac yn amrywiol ac mae hanner The area has a substantial environmental and deheuol y cynllun arfaethedig ym Mharc Cenedlaethol landscape interest and quality and the southern half of Eryri. Roedd harddwch naturiol yr ardal a natur a the proposed scheme is within the Snowdonia National chyd-destun ei thirlun yn cael ei ystyried wrth Park. The natural beauty of the area and its ddylunio’r cynllun arfaethedig. landscape character and context were therefore considered when designing the proposed scheme. Mae’r tir o bobtu’r aber yn cynnwys fflatiau llaid a thywod sy’n terfynnu a chaeau a morfa heli sy’n cael On both sides of the estuary the land comprises of eu pori. Mae hanner deheuol y cynllun arfaethedig yn mudflats and sandflats, which border onto level grassy Nhirlun Ardudwy o Ddiddordeb Hanesyddol Eithriadol fields and saltmarsh used for grazing. The southern ac mae yna sawl nodwedd hanesyddol, gan gynnwys half of the proposed scheme is within the Ardudwy Pont Briwet ei hunan, sydd wedi’i rhestru’n Gradd 2. Landscape of Outstanding Historic Interest and there Dangosir gwerth ecolegol yr ardal gan bresenoldeb are several historical interest features present, nifer o Ardaloedd Cadwraeth Arbennig a Safleoedd o including Pont Briwet itself, which is Grade II listed. Ddiddordeb Gwyddonol Arbennig sydd wedi'u dynodi The area’s ecological value is represented by the ar gyfer amrywiaeth eang o rywogaethau a various Special Areas of Conservation (SAC) and Sites chynefinoedd sy'n cael eu gwarchod. of Special Scientific Interest (SSSI), which have been designated for a variety of protected species and Y DEWISIADAU A YSTYRIWYD habitats. Cafodd sawl dyluniad arall eu hystyried, gan gynnwys cynlluniau ffordd yn unig a rhai ffordd a rheilffordd ALTERNATIVES CONSIDERED cyfun. Several alternative design options, involving road-only and road/rail-combined schemes were considered. Roedd dewisiadau ffordd yn unig yn cynnwys gwella’r ffyrdd A496 ac A487 rhwng Dolfor a Road-only options included improvements to the Phenrhyndeudraeth a fyddai’n golygu codi pontydd existing A496 and A487 between Cilfor and newydd i groesi’r afon 0.6 cilometr ac 1.8 cilometr i Penrhyndeudraeth, new river crossings 0.6km and fyny’r afon o Bont Briwet, pont newydd i lawr yr afon 1.8km upstream of Pont Briwet respectively, a new o bont Briwet a thwnnel o dan Afon Ddyfrdwy. crossing downstream of Pont Briwet and a tunnel Roedd dewisiadau cyfun ffordd a rheilffordd yn underneath the Afon Dwyryd. Rail/road-combined cynnwys adeiladu pont newydd un ai ychydig i fyny’r options involved building the new bridge structure afon, i lawr yr afon neu ar lwybr presennol Pont either slightly upstream, downstream or on the Briwet. existing alignment of Pont Briwet.

Y dewis a ffafriwyd oedd adeiladu pont ffordd a A new rail/road-combined bridge built slightly offline rheilffordd gyfun ychydig oddi ar lwybr y bont and downstream of the existing bridge was the bresennol. Byddai hyn yn gwella’r ffordd bresennol i’w preferred option to improve the existing route for road defnyddwyr ac i ddefnyddwyr y rheilffordd a gellid and rail users and complete the works within one gwneud y gwaith mewn un rhaglen yn hytrach na construction programme, rather than requiring two chael dau gynllun gwahanol a fyddai’n ymestyn effaith different schemes and prolonging the construction y gwaith adeiladu am gyfnod hwy. impacts.

Cafodd pum dewis ar gyfer trefnu’r traffig ar gyffordd Five options for the new traffic provision at the Cambrian View a Ffordd Harlech gyda’r A487 eu Cambrian View and Harlech Road junction with the cyflwyno’i i’r cyhoedd ddiwedd 2010. Roedd y rhan A487 were presented to the public in late 2010. The fwyaf o’r ymatebion yn ffafrio traffig ddwy ffordd ar majority of favourable feedback was for two-way hyd Cambrian View a Ffordd Harlech. traffic along Cambrian View and Harlech Road. Y CYNLLUN ARFAETHEDIG THE PROPOSED SCHEME Prif amcan y cynllun arfaethedig yw rhwystro The main aim of the proposed scheme is to prevent dadgomisiynu Rheilffordd Arfordir y Cambrian a gwella the decommissioning of the Cambrian Coast Railway amodau ar gyfer defnyddwyr ffordd, yn enwedig loriau Line and improve conditions for road users, especially trymion, drwy adeiladu pont newydd, well. Bydd llai o Heavy Goods Vehicles, by replacing and upgrading the dagfeydd i gerbydau ysgafn hefyd wrth groesi’r afon. existing structure. Congestion would also be reduced

Y canlyniad allweddol fydd y bydd yn haws teithio at the river crossing with fewer delays for light rhwng de a gogledd Gwynedd. vehicles. The key outcome will be to increase

accessibility between north and south Gwynedd and

Bydd y cynllun arfaethedig yn golygu adeiladu pont beyond. newydd i gario’r rheilffordd bresennol a ffordd newydd ddwy lôn gyda darpariaeth ar gyfer cerddwyr a beicwyr The proposed scheme involves the construction of a dros Afon Ddwyryd. Bydd y gwaith hefyd yn golygu new bridge crossing to carry an existing railway and a gwella’r ffyrdd tuag ati o’r de a’r gogledd. Bydd y new two lane carriageway with provisions for bont reilffordd newyd dyn cael ei hadeiladu i lawr yr pedestrian and cycle access over the Afon Dwyryd. afon o’r bont bresennol a bydd y bont ffordd newydd The work would also involve improvements to the yn yr un fan a’r bont bresennol, ond bydd y ddwy yn existing north and south road approaches. The new cael eu cysylltu i ffurfio un strwythur. rail bridge would be constructed downstream of the existing bridge and the new road bridge would be in Bydd y ddwy bont yn cael ei hadeiladu o drawstiau the same location as the existing bridge, but both concrid wedi’u rahgdynhau ar bennau croes concrid yn would be connected to form one structure. cael eu cynnal ar golofnau concrid llydan yng ngwely’r afon ac ar ddwy sedd ar argloddiau llydan uchel ar Both bridge superstructures would be constructed bob pen ar y lan. Bydd dwy bont arwahan ar gyfer y from pre-stressed beams, supported on rheilffordd a’r ffordd, a bydd pont y rheilffordd yn cael concrete crossheads and new large diameter concrete ei hadeiladu o flaen pont y ffordd. Fodd bynnag, piles/piers founded in the river channel and two bydd y colofnau ar un llinell a bydd y pennau concrid a bankseats founded on widened and raised approach fydd yn eu cynnal yn cael eu cysylltu. embankments at either end. The railway and road superstructures would be separate, as the railway Bydd aliniad newydd y rheilffordd yn golygu y bydd yn bridge would be constructed before the road bridge. rhaid symud gorsaf Llandecwyn tua 5 metr ymhellach However, the piers for both bridges would be along a i’r gorllewin. Mae hynny’n golygu y bydd ar gau dros single line and the supporting concrete crossheads dro. would be connected.

Bydd y bont ffordd newydd yn cael ei chysylltu â The new rail alignment would require Llandecwyn phont y rheilffordd ar yr ochr i fyny’r afon. Bydd Station to be relocated further westwards by ganddi ddwy lon ar gyfer traffig ffordd a hefyd lwybr approximately 5m, which would result in temporary cerdded a beicio ar wahân. Ni fydd yr un o’r ddwy disruption to the use of this facility. bont yn is na gwaelod y bont bresennol (ar gais Asiantaeth yr Amgylchedd Cymru). Dylunnir y ffordd The new road bridge would be connected with the rail newydd ar gyfer cyflymder o 40 milltir yr awr. Bydd y bridge on the upstream side and would provide a two- ffyrdd at y bont yn cael eu lledu i fod yr un lled â’r lane carriageway for road traffic and include a ffordd dros y bont. separate cycleway/footpath. The underside of both the rail and road bridges would be no lower than the Ni fwriedir cynnwys pontydd goleuadau na cyfarpar existing bridge (as requested by Environment Agency gwybodaeth traffig fel rhan o’r cynllun arfaethedig. Wales). The design speed for the new road is 40mph. Ar hyn o bryd, byddai ychydig o arwyddion ffyrdd a The widened approach roads would coincide with the mân eitemau eraill cysylltiedig, ond bydd lle yn union y existing road/rail width. bydd y rhain yn cael eu gosod, a’u math, yn cael ei gadarnhau ar ôl cynnal archwiliad diogelwch a rhagor No lighting, gantries or traffic information equipment o ddylunio manwl. is proposed as part of the scheme. As at present, there would be a small number of associated road signs and other minor items, but the exact location and type of these would be confirmed following a site safety audit and further detailed design.

ASESIAD EFFEITHIAU AMGYLCHEDDOL ENVIRONMENTAL IMPACT ASSESSMENT Mae'r asesiad amgylcheddol yn ystyried effaith y The environmental assessment considers the effect of cynllun arfaethedig ac, yn ôl y gofyn, y mesurau the Proposed Scheme and, where appropriate, the lliniaru y dylid eu mabwysiadu. Trafodir yr agweddau mitigation measures to be adopted. The topics, hyn, sy'n cael eu dadansoddi'n fanwl yn y Datganiad covered in more detail in the ES, are discussed briefly Amgylcheddol, yn fyr yn y Datganiad Annhechnegol in this NTS. hwn. ANSAWDD AER AIR QUALITY Mae ansawdd yr aer ger y cynllun arfaethedig yn dda The air quality in the vicinity of the proposed scheme ar hyn o bryd ac ni ragwelir y bydd y cynllun is currently good and human health-based Air Quality arfaethedi g yn golygu yr eir y tu hwnt i Safonau Standards during construction and after completion Ansawdd aer yn seiliedig ar iechyd dynol, yn ystod y (operation) are not predicted to be exceeded by the cyfnod adeiladu nac ar ôl hynny (wrth weithredu). proposed scheme.

Disgwylir mai niwrtral fydd llygredd llwch ar eiddo During the construction period, dust pollution is trigiannol yn ystod y cyfnod adeiladu. Disgwylir y expected to have a neutral effect on residential bydd llwch yn effeithio ychydig ar safleoedd cyfagos properties. The effect of dust on nearby protected sy’n cael eu gwarchod, o fewn 200 metr i ffiniau’r sites is expected to be minor adverse within 200 cynllun. Defnyddir mesurau lliniaru i leihau effaith metres of the scheme boundary. Mitigation measures llwch gwaith adeiladu ar y safleoedd yma. Gan mai would be applied to reduce the impact of construction dros dro y bydd y cyfnod adeiladu, ac oherwydd dust on these sites. Due to the temporary nature of graddfa’r cynllun arfaethedig, aseswyd na fyddai the construction phase and the scale of the proposed effeithiau allyriadau o gebyddau’n arwyddocaol. scheme, the significance of construction vehicle emissions has been determined as negligible. Aseswyd hefyd na fyddai’r cyfnod gweithredu’n effeithio’n arwyddocaol ar Ardal Cadwraeth Arbennig The effect of the operational phase of the proposed Pen Llŷn a’r Sarnau ac Ardal o Ddiddordeb Gwyddonol scheme has been determined as negligible for the Arbennig Morfa Harlech. Byddai allyriadau nitrogen Lleyn Peninsula and the Sarnau SAC and Morfa ocsid o g erbydau ffordd yn cael effaith niweidiol Harlech SSSI. Nitrogen oxide emissions from road fechan ar Ardal o Ddiddordeb Gwyddonol Arbennig vehicles could have a minor adverse change on Morfa Morfa Harlech, o fewn 10 metr o ffin y cynllun. Ni Harlech SSSI, within 10m of the scheme boundary. fyddai’r effaith ar dderbynyddion trigianol yn The effect on residential receptors is also considered arwyddocaol. to be negligible.

TREFTADAETH DDIWYLLIANNOL CULTURAL HERITAGE Mae rhan o ben deheuol y cynllun arfaethedig o fewn The southern end of the proposed scheme is situated Tirlun o Ddiddordeb Hanesyddol Eithriadol Ardudwy. partly within the Ardudwy Landscape of Outstanding Mae pen g ogleddol y cynllun arfaethedig ychydig i’r de Historic Interest. The northern part of the proposed o Dirlun o Ddiddordeb Hanesyddol Eithriadol scheme is just south of the Aberglaslyn Landscape of Aberglaslyn. Outstanding Historic Interest.

Mae yna 12 nodwedd archeolegol o fewn neu’n agos There are 12 archaeological features within or very iawn at y Cynllun Arfaethedig a allai gael eu heffeithio. close to the proposed scheme that could be affected. Bydd y mesurau lliniaru yn cynnwys cofnodi’r Mitigation measures would involve recording the nodweddion a effeithir cyn eu malurio: affected features in advance of their destruction: • Nodwyd pum olion archeolegol y tu fewn i goridor • Five archaeological remains were identified within y cynllun arfaethedig, gan gynnwys cei, grwynau, the proposed scheme corridor, including a wharf, glanfa llidart lechi a gwahanol waliau terfyn. groynes, slate gate piers and various boundary • Mae’r adeiladai hanesyddol sydd o fewncoridor y walls. cynllun arfaethedig yn cynnwys Pont Briwet, y • Three historic buildings are within the proposed Tolldy a safle Gwaith Powdr Cooke’s. scheme corridor, including Pont Briwet, the Toll • Mae nifer o elfennau tirlun hanesyddol o fewn House and the Cooke’s Explosives Works site. coridor y cynllun arfaethedig. Mae’r rhain yn • Several historic landscape elements are within the cynnwys anheddiadau (Penrhyndeudraeth) a proposed scheme corridor. These include bryniau (y Moelwyn). settlements (Penrhyndeudraeth) and hill Mae traphont Pont Briwet yn adeilad rhestredig Gradd formations (Moelwyn range). 2. Bydd yn cael ei chofnodi’n llawn â chofnod adeilda Pont Briwet viaduct is Grade II listed and would be Lefel 4 cyn ei dymchwel o dan Ganiatâd Adeilad fully recorded prior to its removal under Listed Rhestredig. Ni fydd unrhyw nodweddion rhestredig Building Consent. No other listed features would be eraill yn cael eu heffeithio. Does yna ddim Henebion affected and there are no Scheduled Ancient Rhestredig o fewn 500 metr i’r cynllun arfaethedig ond Monuments within 500m of the proposed scheme. An bydd cynllun cadw golwg archeolegol yn chwilio am archaeological watching brief would identify any unrhyw nodweddion heb eu darganfod. undiscovered features during the works. TIRLUN LANDSCAPE Mae rhan o ardal yr astudiaeth ym Mharc Cenedlaethol The study area falls partly within the Snowdonia Eryri ac felly mae’r tirlun a’i fwyniant gweledol yn cael National Park and as such the landscape and its visual yr warchodaeth gadarnaf sydd i’w chael yng Nghymru. amenity are afforded the highest levels of protection O ganlyniad, mae’r tirlun yn cael ei gydnabod am ei in Wales. As a consequence this landscape is nodweddion arbennig ac am bwysigrwydd ei recognised for its special qualities and the importance nodweddion sy’n cyfrannu at ei gymeriad. of its landscape features in contributing to its Amgylchedd y môr yw elfen bennaf ardal yr astudiaeth character. The maritime environment forms the main ac mae nifer o ddynodiadau ecolegol o bwysigrwydd element of the study area and is also covered by a rhyngwladol a chenedlaethol arno yntau hefyd. number of international and nationally important ecology designations. Ystyrir fod y Bont Briwet bresennol, sydd wedi’i rhestru’n Gradd II, yn nodwedd eiconig yn ardal yr The existing Grade ll listed Pont Briwet is considered astudiaeth ac yn un sy’n dylanwadu i ryw raddau ar ei to be an iconic feature of the study area and one chymeriad ac ar y golygfeydd o’i chwmpas. Mae yna which exerts a degree of influence on the character nifer o olygfeydd cydnabyddedig wedi’u cofnodi o Bont and views of its immediate area. There are a number Briwet o’r ardal gyfagos, yn enwedig o’r Garth tuag at of documented recognised views of Pont Briwet from y de. the surrounding area, particularly from Y Garth to the south. Byddai’r cynllun arfaethedig yn cynnwys dymchwel y Bont Briwet bresennol ac adeiladu yn ei lle bontydd The proposed scheme would include the removal of rheilffordd a ffordd ar wahân, er y byddai’r rhain, o’r the existing Pont Briwet, which would be replaced with rhan fwyaf o leoedd, yn edrych fel un adeiladwaith. a separate railway and road bridge, although in most Hefyd, bydd llwybr y rheilffordd ar yr arfordir yn cael views these would appear as a single structure. In ei symud i gyfarfod â’r bont newydd a bydd y ffordd addition the coastal railway would be realigned on the doll, un lôn, bresennol yn cael ei huwchraddio i fod â approaches to the new railway bridge and the existing dwy gerbydffordd sengl. Yn eu hanfod, bydd y single lane toll road upgraded to a dual single pontydd newydd a’r adeiladwaith i’w canlyn yn cael eu carriageway. In essence the proposed replacement hadeiladu ar ffurf a graddfa wahanol y gellir eu bridges and the adjacent infrastructure would be of a hystyried yn gyffredin ac yn gyferbyniol. different scale and form, which could be considered as commonplace and contrasting. Effaith cyffredinol y cynllun arfaethedig yw y bydd yn dal effeithiau niweidiol ar y tirlun ac ar gymeriad The overall effect of the proposed scheme would gweledol yr arfordir a’r wlad o’i gwmpas, ond dim ond result in continuing adverse effects on both the rhai lleol fydd y rhain. landscape ansd visual character of the coast and its hinterland, but these would be of a localised nature. ECOLEG A CHADWRAETH NATUR Mae Pont Briwet a’r cynllun arfaethedig yn Ardal ECOLOGY AND NATURE CONSERVATION Cadwraeth Arbennig Pen Llŷn a’r Sarnau, sy’n safle o Pont Briwet and the proposed scheme are situated bwysigrwydd rhyngwladol sy’n cynnwys trwyn Penrhyn within the Lleyn Peninsula and the Sarnau Special Llŷn, Bae Tremadog a hanner gogleddol Bae Area of Conservation (SAC), which is an internationally Ceredigion. Mae’n cynnwys Aber Afon Dwyryd hyd at important marine site encompassing the end of the derfyn dylanwad y llanw ym Maentwrog. Lleyn Peninsula, Tremadog Bay and the northern half of Cardigan Bay. It also includes the Dwyryd estuary Mae rhannau o’r ffyrdd cyswllt i’r gogledd a’r de a’r up to the limit of tidal influence at Maentwrog. rheilffordd hefyd ger terfyn y safle hon. Ar ac o gwmpas Pont Briwet, mae’r Ardal Cadwraeth Arbennig Sections of both the northern and southern approach yn cynnwys Safle o Ddiddordeb Gwyddonol Arbennig roads and the railway are also located adjacent to the Morfa Harlech. Gallai’r cynllun arfaethedig effeithio ar edge of this site. Within and surrounding Pont Briwet, y safleoedd hyn drwy golli cynefin yr aber ac amharu the SAC is underpinned by the Morfa Harlech Site of ar nodweddion ecolegol, dros dro neu’n barhaol. Special Scientific Interest (SSSI). The proposed scheme could affect these sites through the Mae Gwarchodfa Natur Gwaith Powdwr yn cael ei permanent loss of estuary habitat and temporary rheoli gan Ymddiriedolaeth Bywyd Gwyllt Gogledd disturbance to ecological features. Cymru. Mae’n cynnwys 28 hectar o nifer o gynefinoedd gan gynnwys: coetir, prysg, rhostir, Gwaith Powdwr Nature Reserve is managed by the creigiau moel a dyfroedd agored. Bydd y cynllun Wildlife Trust (NWWT) and comprises a arfaethedig yn arwain at golli’n barhaus rhimyn cul o wide range of habitats, including: woodland, scrub, dir ar derfyn y safle. heathland, bare rock and open water. The proposed scheme would result in the permanent loss of a narrow strip of land from the site boundary.

Mae’r rhan fwyaf o’r ardal yn cynnwys rhostir a phorfa The majority of the local area comprises of heathland wedi’i wella sy’n rhedeg at Afon Dwyryd: mae and improved grazing pastures that slope down to the cynefinoedd y môr yn yr aber yn cynnwys dolydd heli, Afon Dwyryd: marine habitats within the estuary fflatiau mwd a thywod a thwyni tywod. include salt meadows, mudflats, sandflats and sand

dunes. Cwblhawyd yr arolygon canlynol i gasglu gwybodaeth ynghylch y rhywogaethau a'r cynefinoedd a allasai Surveys for the following were completed to gather gael eu heffeithio gan y cynllun arfaethedig, information about the species and habitats possibly cynefinoedd (gan gynnwys morfa heli), ymlusgiaid, affected by the proposed scheme; habitats (including adar yn nythu a gaeafu, ystlumod, dyfrgwn a llygod y the saltmarsh), reptiles, breeding and wintering birds, dŵr. bats, otters and water voles.

Mae’r aber yn gynefin i wahanol rywogaethau sy’n cael The estuary and Afon Dwyryd provide habitat for eu hystyried yn dderbynyddion sensitif, gan gynnwys various species that are considered sensitive pysgod sy’n mudo, adar yn gaeafu, dyfrgwn a rhai receptors, including migratory fish, breeding and planhigion. Mae Afon Dwyryd yn addas ar gyfer wintering birds, otters, bat species and certain flora. dyfrgwn ac adar yn nythu gyda choridor yr afon yn llwybr hedfan ac yn lle bwydo i ystlumod. The proposed scheme would cause various adverse

impacts of differing scales on the species, habitats and Bydd y cynllun arfaethedig yn cael sawl effaith wael o protected sites present both during its construction wahanol raddfeydd ar y rhywogaethau a'r cynefinoedd and operation. These include direct loss of habitats a'r ardaloedd gwarchodedig wrth ei adeiladu a phan for reptiles, otters and breeding/wintering birds, fydd ar agor. Mae hyn yn cynnwys colled potential temporary disturbance to species using the uniongyrchol o gynefin ar gyfer ymluagiaid, dyfrgwn, site, possible pollution of watercourses and effects on adar yn bridio ac yn gaeafu, gallai amharu dros dro ar the integrity of protected sites. rywogaethau’n defndydio’r safle a gallai, efallai lygru cyrsiau dŵr ac amharu ar gyfanrwydd safleoedd sy’n These impacts would be reduced by various mitigation cael eu gwarchod. measures including: capture and translocation of

reptiles, fencing off sensitive areas, timing of Gellir lleihau'r effeithiau hyn gyda gwahanol fesurau clearance work to avoid the bird nesting season, lliniaru, gan gynnwys: dal a symud ymlusgiaid, ffensio sensitive landscaping and water quality protection ardaloedd sensitif, amseru gwaith clirio fel nad yw’n measures. cyd-fynd â’r tymor nythu, plannu coed, tirlunio’n sensitif a mesurau i warchod ansawdd dŵr. GEOLOGY AND SOILS The geology of the area is Upper Cambrian and DAEAREG A PHRIDDOEDD composed of marine/estuarine deposits in the Afon Cambrian Uchaf yw daeareg yr ardal ac mae’n Dwyryd river valley, which overlie the Ffestiniog Flags cynnwys g waddodion mâr ac aber yn nyffryn Afon formation of sandstones and mudstones. No Dwyryd sydd uwchben ffurf o garreg dywod a charreg protected geological sites are located within or directly fwd Fflagiau Ffestiniog. Nid oes unrhyw safle adjacent to the proposed scheme. The baseline ddaearegol y tu fewn nag yn union gerllaw (o fewn 1 conditions in terms of geology, hydrogeology and cilometr) i’r cynllun arfaethedig. Ychydig o werth nad geomorphology are valued as low and generally of diddordeb na phwysigrwydd lleol sydd i’r amodau local interest and importance. gwaelodlin o ran daeareg, hydroddaeareg na geomorffoleg. The only mitigation measure associated with geology is basic radon protection during construction. Soil Yr unig fesur lliniaru sy’n gysylltiedig â daeareg yw handling and storage mitigation measures are also amddiffyniad sylfaenol rhag radon yn ystod y gwaith proposed during construction. adeiladu. Bwriedir hefyd gyflwyno mesurau lliniaru wrth drin a chadw pridd yn ystod y cyfnod adeiladu. During the construction period, adverse impacts could occur as a result of the exposure of localised areas of Gallai drw g effeithiau ddigwydd yn ystod y cyfnod contaminated soils. The main potential impacts are: adeiladu o ganlyniad i bridd halogedig yn cyrraedd • Exposure of construction workers and local rhai mannau. Yr effeithiau posibel yw: residents to contaminants, and; • Bodd gweithwyr adeiladu a thrigolion yr adal yn • Leaching and transmission of contaminants into dod i gysylltiad â llygryddion; a the Afon Dwyryd and impact on the water quality • Bodd lly gryddion yn rhedeg ac yn cael eu cario i and integrity of the Lleyn Peninsula and the Afon Dwyryd ac yn effeithio ar ansawdd y dŵr ac Sarnau SAC/Morfa Harlech SSSI. ar Ardal Cadwraeth Arbennig Pen Llŷn a’r Sarnau a Safle o Ddiddordeb Gwyddonol Arbennig Morfa Harlech.

Yr ardaloedd lle mae’r pryder mwyaf yn eu cylch lle The areas identified as being of greatest concern for gallai’r tir gael ei lygru yw Cilfor, gwaith trin carthion causing ground contamination are the Cilfor Welsh Dŵr Cymru a gwaith Cookes / Nobel sydd i’r gogledd o Water sewerage treatment works and the former Bont Briwet. Cooke’s/Nobel works that lie north of Pont Briwet.

Cedwir yn y cof yn ystod y cyfnod adeiladu y gallai The potential for localised areas of contamination to llygryddion fod mewn ambell i fan ar y safle. Yn be present would be taken into account during benodol, mabwysiadir rhagofalon iechyd a diogelwch a construction. In particular, appropriate health and gofynnir am gyngor pellach os deuir ar draws amodau safety precautions would be adopted and further annisgwyl neu anarferon ar y ddaear. advice would be sought if unexpected or unusual ground conditions were encountered. DEFNYDDIAU Mae’r cynllun arfaethedig yn golygu dymchwel y bont MATERIALS bresennol ac adeiladu pont newydd yn yr un fan o The proposed scheme involves the demolition of an ddefnyddiau modern. existing bridge and the construction of a new bridge in the same location using modern standard materials. Gan mai ar y cyfnod amlinellol y mae’r cynllun arfaethedi g, dim ond amcangyfrion ar y gorau yw As the proposed scheme is at an outline stage of llawr o’r manylion ynghylch ffynonellau a chyfeintiau design many of the details regarding materials defnyddiau a mannau adeiladu, Unwaith y bydd volumes, sources and construction areas are only best contractwr wedi’i adeiladu, bydd y gwaith dylunio estimates at present. However, once a contractor has manwl yn cychwyn, bydd y rhain yn cael eu datblygu’n been appointed and detailed design work commences, fanylach a gallai rhai newid. these values and areas would be developed in more detail and may change. Cafodd nifer o ystyriaethau eu cynnwys yn y dyluniad amlinellol i ddefnyddio cyn lleied ag sydd bosibl o A number of considerations have been incorporated ddefnyddiau, lleihau effeithiau trin a defnyddio into the outline design to minimise materials use and cymaint ag sydd bosibl o ddefnyddiau eilaidd. Ystyrir handling impacts and maximise the use of recycled or a fydd ang en mesurau pellad i leihau’r effeithiau ar ôl secondary materials. Further measures are paratoi dyluniad manwl ac unwaith y penodir considered necessary to reduce the impacts during the contractwr. detailed design phase and once a contractor has been appointed. SŴN A DIRGRYNIAD Ychydig fyddai sŵn dros dro yn ei amharu yn ystod y NOISE AND VIBRATION cyfnod adeiladu gan fod cartrefi pobl ymhell o’r gwaith Temporary noise impacts during the construction adeiladu. Rhagwelir y bydd lefelau dirgryniadau’r period would be small due to there being large gwaith peilio ymhell islaw’r lefel a argymhellir o distances between residential dwellings and the area 10mm/s p.p.v. Mae hyn eto oherwydd y byddai’r where construction activities would take place. gwaith peilio ymhell oddi wrth gartrefi pobl. Predicted vibration levels from piling activities would be well below the recommended level of 10mm/s Byddai llai o sŵn led yr ardal astudiaeth yn ystod y p.p.v. This is again due to the large distance between cyfnod gweithredu na heb y cynllun arfaethedig.Ni piling activities and residential dwellings. fyddai’r rhan fwyaf o dderbynyddion yn profi unrhyw effaith o’r cynllun arfaethedig. Hebddo, byddai’r rhan During the operational phase of the proposed scheme fwyaf yn profi ychydig o effeithiau drwg. the effects of noise across the study area would be of a lesser extent than the predicted situation without Ni ragwelir y bydd unrhyw gartref o fewn 300 metr o the proposed scheme. With the proposed scheme the Bont Briwet yn cael cyfraniad ychwanegol o fwy na majority of receptors would experience no effect 1dB o sŵ n oddi wrth y ffordd newydd at y lefel compared with the majority of receptors experiencing gyffredinol o sŵn ac ni fyddai yr un, felly, yn gymwys i a slight adverse effect without the proposed scheme. gael insiwleiddiad sŵn. No dwellings within 300m of Pont Briwet are predicted to have a contribution of greater than 1dB from the Byddai’r sŵ n a ddeuai oddi wrth y cynllun arfaethedig new/altered road to the total overall noise level and yn yr ardal astudiaeth yn llai na phe na byddai’r therefore would not qualify for noise insulation. cynllun yn cael ei adeiladu. Bydda’r cynnydd yn digwydd dros gyfnod o 15 mlynedd ac ni fyddai i’w The proposed scheme would result in increases in glywed bob amser. Byddai’n llai na 3dB(A). noise level across the study area, but these would be lower in magnitude than for the predicted situation without it. The increases would occur over a 15 year period and would not be perceptible as all increases would be of less than 3dB(A). EFFEITHIAU AR DEITHWYR EFFECTS ON ALL TRAVELLERS Cafodd yr effeithiau y gallai’r cynllun arfaethedig ei The potential effects of the proposed scheme on gael ar deithwyr mewn cerbydau ac ar rai heb vehicle travellers and non-motorised users (which gerbydau (sy’n cynnwys cerddwyr, beicwyr, include pedestrians, cyclists, equestrians, rail users marchogwyr, defnyddwyr y rheilffordd a defnyddwyr and users of the Afon Dwyryd) were assessed. Afon Dwyryd) eu hasesu. The current and future users of Pont Briwet and both Cafodd defnyddwyr presennol Pont Briwet, a’r rhai a approach roads and also users of the sections of the fydd yn ei defnyddio yn y dyfodol, eu hystyried, y rhai A487 and the A496 between Cilfor, Maentwrog and yn defnyddi’r ddwy ffordd tuag ati a hefyd Penrhyndeudraeth, which provide the nearest ddefnyddwyr rhai rhannau o’r A487 a’r A496 rhwng alternative route for travellers currently unable to use Cilfor a Phenrhyndeudraeth, sef y ffordd amgen nesaf Pont Briwet, were considered within the assessment. i deithwyr na all ddefnyddio Pont Briwet Most adverse impacts would occur during the Byddai’r rhan fwyaf o’r effeithiau drwg i’w teimlo yn construction period when disruption to normal travel ystod y cyfnod adeiladu pan fydd patrymau teithio patterns is likely to occur and affect vehicle travellers arferol yn debyg o gael eu hamharu – i gerbydau a and non-motorised users. However, during the theithwyr eraill. Fodd bynnag, yn ystod y cyfnod operational phase, beneficial impacts are expected for gweithredol, disgwylir y bydd pob teithiwr ar ei ennill. all travellers as a result of the improved design Bydd y safon dylunio’n well a bydd llwybr cerdded a standard of the bridge and approach roads and the beicio o un pen i’r cynllun i’r llall. provision of a cycle/footway through the proposed scheme.

ASEDAU CYMUNEDOL A PHREIFAT COMMUNITY AND PRIVATE ASSETS Mae cyfnaswm ôl troed y prosiect tua 5 hectar, a thua The total footprint of the proposed scheme is hanner hyn eisoes yn cael ei ddefnyddio gan y approximately 5 hectares, with nearly half of this rheilffordd a’r draphont. Bydd y cynllun arfaethedig being the existing railway land and viaduct. The angen, yn barhaol, tua 4.2ha o dir gan gynnwys tir y proposed scheme would involve the permanent loss of rheolffordd a’r ffyrdd presennol. Mae’r rhan fwyaf o’r approximately 4.2ha of land, including the existing tir sy’n cael ei effeithio yn cael ei ddefnyddio gan y railway and roads. The majority of land affected is rheilffordd a’r ffyrdd neu’n dir amaethyddol a morfa existing roads, railway, agricultural land and heli. Mae’r gweddill yn cynnwys tir yr aber, tir saltmarsh. The remainder consists of land within the cymunedol, ystâd ddiwydiannol a thir mewn estuary, community land, industrial estate and perchnogaeth breifat. Yn ystod y cyfnod adeiladau, privately-owned land. During construction temporary bydd angen cyfanswm o tua 0.7ha o dir gweithio dros working areas, easements and construction facilities dro, hawddfreintiau a darpariaethau ar gyfer adeiladu. would constitute approximately 0.7ha.

Mae’r tir sy’n cael ei effeithio’n uniongyrchol gan y The land directly affected by the proposed scheme is cynllun arfaethedig yn cael ei ystyried yn ‘wael iawn’ o classed as ‘very poor’ in terms of agricultural ran ei gynhyrchedd a‘i hyblygrwydd amaethyddol. Y productivity and versatility. Agricultural use along the prif ddefnydd tir amaethyddol ar goridor y cynllun proposed scheme corridor is predominantly low arfaethedig yw magu da byw. Bydd y tir a fydd yn intensity livestock production. cael ei gymryd dros dro yn cael ei roi’n ôl i'r gwahanol dirfeddianwyr ar ôl gorffen y gwaith adeiladu. The most significant impacts on land use would arise from the demolition of the tollhouse, temporary Mae’r rhan fwyaf o’r adnoddau cymunedol ym mhrif disruption to access to residential properties and anheddiad Penrhyndeudraeth a Phorthmadog i’r agricultural land and agricultural land take. The gogledd ac i’r gorllewin. Bydd pont dros dro yn cael temporary areas of land take would be returned to the ei chodi yn ystod y cyfnod adeiladu i draffig ddal i allu respective landowners following construction. croesi Afon Dwyryd a rhag i bobl gael eu cadw oddi wrth adnoddau cymunedol yn ystod y cyfnod hwnnw. Community facilities are predominantly located within Ar ôl gorffen y cynllun, un o fanteision pennaf y the main settlements of Penrhyndeudraeth and cynllun arfaethedif fydd gwell rhwydwaith o ffyrdd ac Porthmadog to the north and west. A temporary y bydd yn haws cyrraedd adnoddau cymunedol. causeway built during the construction phase would continue to allow traffic over the Afon Dwyryd and reduce the severance of communities from facilities during this time. On completion of the work, a major benefit of the proposed scheme would be the improved road network and access to community facilities.

DRAENIO'R FFORDD AC AMGYLCHEDD Y DWR ROAD DRAINAGE AND THE WATER Cafodd i ba raddau y gallai prif gyfnodau’r cynllun ENVIRONMENT arfaethedig (adeiladu a gweithredu) effeithio ar The main phases of the proposed scheme ansawdd dŵr, ar batrymau draenio ac ar beryglon (construction and operation) were assessed for the llifogydd ei asesu. potential to result in impacts on water quality, drainage patterns and flood risk. Y brif nodwedd draenio dŵr wyneb yw Afon Dwyryd, y mae ei haber yn yr ardal astudiaeth ac y mae pont The main surface water feature is the Afon Dwyryd, Briwet yn ei chroesi. Mae cyrsiau dŵr eraill yn yr which is estuarine within the study area and spanned ardal astudiaeth yn cynnwys nentydd dienw a by Pont Briwet. Other watercourses within the study draeniau tir i’r gogledd o aber Afon Dwyryd a nentydd area include unnamed streams/land drains to the i’r de o’r aber, dwy o’r nentydd mwyaf y rhwydwaith north of the Dwyryd estuary and streams to the south yw Ffos Tŷ Newydd a Nant Yr Efail. of the Dwyryd estuary; two of the larger named streams in this network are the Ffos Ty Newydd and Mae data Asiantaeth yr Amgylchedd yn awgrymu fod the Nant Yr Efail stream. dŵr croyw a dŵr aber yng nghyraeddiadau Afon Dwyryd o safon dda, ar hyn o bryd ac yn ôl a ragwelir. Environment Agency Wales data suggest that both the freshwater and estuarine reaches of the Afon Dwyryd Mae rhannau o’r cynllun arfaethedig yn treiddio i share good existing and predicted future water quality. orlifdir Afon Dwyryd, yn enwedig ar bennau gogleddol a deheuol wrth gyrraedd Pont Briwet. The proposed scheme in part encroaches onto the floodplain of the Dwyryd, particularly at the northern Gallai gwaith adeiladu halogi neu lygru cyrff dŵr and southern approaches to Pont Briwet. cyfagos. Gallai gwaith adeiladu yn y sianel achosi, dros dro, gynnydd sylweddol yn y llwyth gwaddodion Construction works have the potential to cause drwy amharu ar wely’r afon ac ar y casgliad o contamination/pollution of adjacent waterbodies. In- waddodion a mwd. Pan fo gwaith yn cael ei gynnal channel construction activities could temporarily add ger neu’n agos at gyrsiau dŵr, gallai cael gwared ar significant sediment loads to watercourses due to the lystyfiant ac amharu ar bridd, yn enwedig wrth i ddŵr disturbance of river bed materials/existing deposits of redeg ar wyneb y man gwaith, olygu bod dŵr ffo yn sediment and silt. Where works are taking place llawn mwd. Gallai llwybrau cerbydau a pheiriannau adjacent or nearby to watercourses, stripping of adeiladu hefyd droi’n fwdlyd a gallai’r mwd gyrraedd vegetation and disturbance of soils in combination dŵr ffo. with flows of surface water runoff across works areas has the potential to generate runoff that is high in silt. Ffynonellau eraill posibl o lygredd yw tanwydd ac olew Haul routes used by construction vehicles and plant o’r peiriannau adeiladu, defnyddiau megis sment a may also accumulate deposits of mud and are another choncrid a gwastraff adeiladu (gwastraff solet a dŵr potential source of silty runoff. gwastraff). Other potential sources of pollution include fuels and Ni fyddai yna unrhyw newid i’r perygl bychan y byddai oils from construction equipment, materials such as aber Afon Dwyryd yn cael ei llygru gan ddŵr ffo cements and concrete and construction waste (solid arferol oddi ar y ffordd. Ni fydd yna unrhyw effaith waste and wastewater). chwaith ar y peryglon presennol o ollyngiadau damweiniol sy’n gysylltiedig â thraffig yn croesi’r aber There would be no change to the existing low yn ystod cyfnod adeiladu’r cynllun arfaethedig. pollution risk to the Dwyryd estuary from routine discharges of highway runoff. There will also be no Tybir mai yn y tymor byr ac yn ystod y cyfnod impact on the existing risk of an accidental spillage adeiladu y ceid yr effeithiau mwyaf ar amgylchedd y associated with traffic crossing the estuary during the dŵr wyneb. Unwaith y bydd hyn wedi’i orffen, bydd construction phase of the proposed scheme. llawer iawn llai o debygolrwydd yr effeithir ar ansawdd dŵr gan y bydd llawer iawn llai o waith ar y safle. The greatest likelihood of effects on the surface water environment is considered to be during the short-term Bydd mesurau lliniaru, yn seiliedig ar ymarfer adeiladu construction phase. Once this is complete, the da, a rheolaeth dda, yn lleihau’r effeithiau y gallai potential for water quality impacts will be significantly cyfnodau adeiladu a gweithredu’r cynllun arfaethedig lower as on-site activity will be considerably reduced. ei gael ar amgylchedd y dŵr wyneb, gymaint fel na fyddai’r ffeithiau gweddilliol cyffredinol yn Mitigation measures based on good construction arwyddocaol. practice and management will reduce the potential effects of the construction and operation phases of the proposed scheme on the surface water environment, such that the overall residual impacts will not be significant.

5909

Drain TCB 3306 Tyn-y-Ffrwd

21.3m

Bryn Tyn-y-Ffrwd Islwyn Terrace

Drain Drain

Meusydd-llydain 6100 Penfro

0700 2100 4600 5200 The Studio

Path (um) Penrhyndeudraeth

0700 2100 5200 5700 6500 Meusydd The Drain -Uydain Studio Drain Glenrose

Path (um)

Path (um)

7495 Hyfrydle Terrace 3893 Y Bryn

Drain 31.7m Canol-cae Griffin Hotel 5591

2390

Gorffwysfa 4488 2588 El Cambrian View Bryn Eirian Sub Sta Bryniau-hendre Bro Llewelyn Llysfryn Issues

6687 29.9m BM 30.93m Adwyddu Garreg Wen Isaf 2585 Llywn

Onn

MOELWYN

SP Pond Smithy TREM Y

Strud y Eirianfa 6681 Castell 3381

15.8m 6591 Sibrwd Yr Awel A487 Holy Trinity Heol Eryri 4080 Lay-by Stad Ddiwydiannol 6778 PW Llys Gorsaf Tren y Garth Church 2077 i/ to Porthmadog LB Penrhyndeudraeth 4776 1075 23.2m Penrhyndeudraeth Trustan

Bronturnor 5875 Industrial Estate Caerelan

El El Sub Sta Rail Station Sub 23.8m

Perthi Trewyn Sta

Glentoran

ADWYDDU TCB 2270 3169 LB 1470

Ysbyty Bronygarth

(Bronygarth Hospital) Gorwel Maelor MAES HENDRE Gwarchodfa Natur 24.4m Level Crossing Gwellianau Cyffordd/ Ffordd MAES TEG Gwaith Powdwr

Offices Path (um) Hendre Hall Penrhyndeudraeth Nature Reserve Pond Path 7560 8759

El 6859 Sub Sta Penrhyndeudraeth Road/ Cae- Ednyfed TREM-YR-WYDDFA 6256 27.1m 8056 Junction Improvements

Drain

Path

6952

5250 Path (um)

7348

8945 Gwaith Trin 4444

Pond 5944

MP ETL 117 Carthffosiaeth Drain Tolldy i'w Afon Dwyryd Path Sewage (um) dymchwel Pond

Drain I Fron-oleu 4139 Treatment Works Toll House to

Drain

Path (um) be demolished

4933 Gwelliant Ddynesu Parc Busnes Eryri

(Snowdonia Business Park)

Drain Gogleddol Pont Briwet

Ynys-fawr 4628 Traphont i'w Gael ei Drain Pont Briwet Northern Pont

Mean High Water Sand Newid a'i Wella Sand Drain Sand Approach Improvement Garth Bengan

Mean High Water SP Briwet Viaduct Replaced and 3522 MP 117.25

MP Drains Drain

117.5 2419 Improved

Drain

Path (um)

4215 Drain

Mean High Water

Sand

Tyddyn Heulyn

2707

Tremadog Bay

Afon Dwyryd ED Bdy ED Bdy Traeth Bach CCLW CCLW Sand Afon Dwyryd

1200 2200 Gwellianau Ffordd Terfyn Sand Gwelliant Ddynesu Sand Sand Sand Ddeheuol Pont Briwet Llandecwyn i A496 Pont Briwet Southern Llandecwyn Halt to A496

Mean High Water Afon Dwyryd Terfyn CCLW Approach Improvement Road Improvements Sand

ED Bdy Llandecwyn Afon Dwyryd Halt Sand

ED Bdy to Afon Dwyryd CCLW Gwaith Trin Dŵr Water Treatment A496 i/ Works Maentwrog

Sand

Cilfor Tremadog Bay Sand

Sand Traeth Bach

Sand Sand Mean High Water High Mean